From the introduction:
In the Flame System, it is humans that hold sway in the majority of societies, but that is not to say they are the only members. Instead, a myriad of alien life forms can be found serving, interacting and sometimes leading humanity's actions. These are not native intelligences; prior to man, it is thought that the Flame System was home to no truly sapient species. These are Uplifts, hybrid beings created from alien and human DNA, and raised to human-equivalent intelligence through genetic engineering. All of the inhabited worlds of the Flame System are home to Uplifts, and they come in all manner of shapes, sizes and outlooks. This book details some of the more common and human-like Uplifts, detailing their appearance, mannerisms and attitude, as well as their acceptance into human society. Also, details are given for creating Uplift Hosts for Exile Player Characters to add an extra dimension to playing In Flames.